1. Field of the Invention
The present invention relates to a semiconductor device and to a method of fabricating the same. More specifically, the present invention is directed to a semiconductor device having a non-volatile memory cell and to a method of fabricating the same.
2. Description of the Related Art
Non-volatile memory cells continuously hold their stored data even when their power supplies are interrupted. Typically, a non-volatile memory cell has a gate stack structure. Specifically, a non-volatile memory cell has a gate stack and a source/drain formed at opposite sides of the gate stack. The gate stack includes a gate insulation layer, a floating gate, an intergate dielectric, and a control gate which are sequentially stacked on a substrate. Charges are introduced to the floating gate through a tunnel insulation layer to be stored therein. The stored charges set a threshold voltage of the cell. A non-volatile memory cell stores data using the cell threshold voltage.
The fabricating a non-volatile memory device includes a photolithographic process following the formation of the intergate dielectric. Specifically, the photolithographic process is carried out to form the control gate on the intergate dielectric. In this case, the intergate dielectric may be damaged during the photolithographic process. Also, the intergate dielectric may be additionally damaged during a subsequent process in which a spacer is formed. Damage to the intergate dielectric degrades the reliability of the non-volatile memory device because if charges stored in the floating gate migrate through the damaged intergate dielectric during operation of the cell, the threshold voltage of the cell fluctuates. Hence, the data stored in the cell is altered.
Also, it might be desirable to produce a semiconductor device in which a logic transistor is integrated with the non-volatile memory cell. Conventionally, logic transistors may include a silicide layer to enhance the operating speed thereof. However, a silicide layer can not withstand the high program voltage of a non-volatile memory cell.